Injection blow molding machines, such as disclosed in U.S. Pat. No. 4,076,484 having the same assignee as the present invention, are well known in the art for forming hollow articles, particularly containers of various sizes and shapes. Thermoplastic materials such as polypropylene or polyethylene are heated to a molten, semi-fluid state and are injected into the cavity of an injection mold to form a parison over a removable core or parison pin. Before the material has had an opportunity to completely set, the parison thereon is removed from the injection mold and transferred to a blow mold where pressurized gas or air is blown through the pin to the interior of the parison and causes the parison to expand outwardly in the larger cavity of the blow mold. The expanded parison takes the shape of the blow mold cavity corresponding to a desired shape of the article, and is allowed to set sufficiently to retain that shape thereafter.
In containers of the kind envisioned in the present invention, a highly detailed mouth area is injection molded integrally with a parison portion. The parison portion is then blow molded to the dimensions of the body portion of the finished container. In doing so, a transitional surface is formed between the injected molded mouth area and the larger diameter body portion, which appears as an annular groove on the outside surface of the container just below the mouth area. A container of this kind is illustrated in FIG. 1 of my U.S. Pat. No. 3,977,563.
This groove is not a structural defect from the stand-point of the container's integrity although the groove does decrease the container's stackability slightly. It does, however, represent an irregularity from the standpoint of using the container interchangeably with conventional metal containers in mechanical filling, labeling and packaging equipment. Thus, if the container is designed to specifications which allow it to be filled and packaged interchangeably with conventional containers, the labeling area available on the body portion is substantially smaller than the labeling area of conventional containers. This prevents the application of labels to the containers on existing machinery without substantial modification of those machines to accommodate the differently sized labels.
In addition, in order to provide integral and therefore stronger bale ears for the attachment of a handle to the container, the prior art required that such bale ears must be provided very near the top of the container since these features were required to be provided by injection molding in order to have sufficient detail. In so doing, the containers could not readily be prepared on automatic bale equipment, and were additionally incompatible for this reason.
It is an object of the present invention to provide a container which has a labeling area sufficient for use of the container on conventional labeling machinery without substantial modification of the machinery.
It is a further object of the present invention to provide a container which may be used interchangeably with conventional containers on filling, labeling and packaging machinery.
It is a still further object of the present invention to provide a container with increased wall strength in the region of the transitional surface between the injection molded preform and the blown parison.
It is still further object of the present invention to provide a container in which integrally injection molded bale ears may be provided in the region which would make the container interchangeable with conventional containers on automatic bale equipment.
The object, features, and advantages of the present invention will become more apparent in light of the following detailed description of the preferred embodiment thereof and as illustrated in the accompanying drawings.
According to the present invention, there is provided a container comprising: an injection molded annular mouth portion having detail of high definition, a generally cylindrical body portion blow molded from a parison integrally injection molded with the mouth portion, said body portion having an inside diameter slightly larger than the inside diameter of the mouth portion, and an annular reinforcing region joining the mouth portion to the body portion and forming a transitional surface therebetween, in which the detail of high definition in the mouth portion includes a depending skirt which serves as an outside wall over said reinforcing region providing a suitable sidewall label attachment area over the reinforcing region.